This was in the 2.8 in my Fiero, the car was still running before I pulled the engine but using quite a bit of oil. The piston rings were broke in this cylinder as well.

I'm not planning on fixing this engine I'm going with something else, but I am just curious what causes this? Between the arrows is this indent that goes all the way around the cylinder.

quote Originally posted by Blacksheep: I am just curious what causes this?

quote Originally posted by Blacksheep: The piston rings were broke in this cylinder as well.

That would be my guess...

[This message has been edited by ALJR (edited 05-29-2011).]

Just a guess: if you have bore guage I think you may find more wear -wider- from the bottom of that grove down and thus the reason why the ring didn't score the rest of the cylinder.

BTW: if your ditching the engine, you may want to check the crank out. If its good. you can sell it as most redone 2.8 cranks are NG, whereas you really can't -some do but should not- weld and regind a bad one. There are still a few new Eagle steel cranks left but when they're gone that will be it for new ones.

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How deep is the indent? Was a top ring broken and the bottom one in tact? It looks like this might be about the area where the lower ring would go. Perhaps w/ only one full ring in place the piston was able to wobble more than usual, thus indenting the sleeve over time. Is the indent (groove?) least deep at the ends of the wrist pin?

Thanks for the pic and question. It's always good to come across such issues before we have to solve them ourselves.

-Michael

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"A guy know's he's in love when he loses interest in his car for a few days." -Tim Allen

He who dies with the most toys... still dies.


My '84 Resto

Thanks for the responses.

I don't know if the crank is any good anymore or not, I'm guessing not. Most of the bearings on the piston rods were like this


I'm not sure how deep the indent is, I don't have anything to measure it, I will have to look tomorrow to see what rings were broken, I don't remember. I actually took the engine apart about a year ago I just have been busy since and not got back to working on the car until now.

Was your oil rings carboned up and stuck ? My saturn motor was the same way with excessive wear where the bottom compression ring stopped. Might have something to do with the oil ring not getting the oil and 2nd ring scraping it off, because the oil ring couldn't do the job. Just a my guess on the problem.

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85 GT 3.4
14.9 @ 90 1.9 60' Old TH125/3.06
Unknown New 4T60/3.42

Are all the cylinders like that? Its normal to an extent, the cylinder wears over the life of the engine, that's why people have them bored out.

It's referred to as the cylinder ridge.
If I were to guess more then 90% of all gasoline engines develope a ridge over time.
It is caused by the repetive up and down motion of the piston in the cylinder combined with the heat and fricton produced from the combustion of the fuel. All engine overhaulers have a tool referred to as a ridge reamer to remove that material to facilate the removal of the pistons without braking rings or ring seats of the piston during disassembly of the engine.

[This message has been edited by Indiana_resto_guy (edited 05-30-2011).]

Detonation ... it's a killer.

The crank can be ground. The block can be bored. Even the rods can be repaired. In short, the engine can be rebuilt. But if you can get another engine cheaper, that would be the way to go.

quote Originally posted by TopNotch: The crank can be ground. The block can be bored. Even the rods can be repaired. In short, the engine can be rebuilt. But if you can get another engine cheaper, that would be the way to go.

The cash spent to rebuild that engine can put in a brand new crate 3.4 long block. (GM 12363230) if he wants a drop it in and go easiest to install swap. or go a long way to another bigger swap.

Honestly never EVER put money into rebuilding a 2.8 unless you are building a museum restoration. You will spend close to $1500.00 just for the machine shop work alone.

quote Originally posted by TopNotch: The crank can be ground. The block can be bored. Even the rods can be repaired. In short, the engine can be rebuilt. But if you can get another engine cheaper, that would be the way to go.

A 2.8 crank can be polished, but not reground -IE have the journals welded up and then ground back down to spects, not with much hope for it lasting very long. A reputable machine shop will advise of you such.

I have no real interest in rebuilding the 2.8, I am planning on replacing it with a 3400 but using the 2.8 heads, intake, etc. like FieroSound did, but that's something for a different thread.

This was the only cylinder that had that indent, the others all felt smooth (well except for the rim up at the top which is where that gold colored area is in the picture).
It was the top ring that was broke


Also, this is what the crank looks like for those that were kind of wondering even though its probably impossible to tell anything from the picture.

If the crank has none to minimal scoring on the rod journals it can be reground to a standard undersize no problem. If rod(s) were knocking chances are the journals are too damaged to save. It looks like bearings are available in standard undersizes of .25, .5, and .75 mm, roughly equivalent to .01, .02, and .03". If the crank is savable you should take it to an engine rebuilder, just give it to them, they can use it as a core. Heck, I'd take it myself, my machinist could regrind it no problem. It's an '88 crank so they're a little harder to find.

The crank does look smooth, and the rods were not knocking when I took the engine out, but I don't have the right tools to measure it to see if its worn or anything. There is one scratch I guess I would call it where one of the pistons on the side near the flywheel connected maybe the same one with the indent, not sure. It didn't look deep but again I don't know for sure. I will probably save the crank maybe someone could try to use it later.